US2020008925A1PendingUtilityA1
Laser dimpled stent for prevention of restenosis
Est. expiryMar 23, 2037(~10.7 yrs left)· nominal 20-yr term from priority
A61F 2230/0004A61F 2/06B23K 2101/06B23K 2103/14A61F 2240/001A61F 2002/068B23K 26/355B29L 2031/7534A61F 2/82B23K 26/361
42
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Claims
Abstract
A dimpled stent design has geometrical characteristics, namely dimple width and depth, which generate dimple site specific turbulence and thrust within the blood flow to reduce or eliminate restenosis. The dimpled stent design is produced by laser processing of the stent material to produce different sizes, which may be predicted by a Multiphysics computational model, placements, and spatial layouts of dimples in the stent.
Claims
exact text as granted — not AI-modifiedWhat is claimed is:
1 . A method for laser-assisted preparation of a dimpled stent, comprising the steps of:
(a) directing a laser beam at one or more targeted surface areas of a stent material using an assigned laser track to produce one or more dimples at the targeted surface areas, wherein the laser track is assigned a heat flux boundary with a moving laser beam defined by the equation:
-
k
[
(
∂
T
∂
x
)
+
(
∂
T
∂
y
)
+
(
∂
T
∂
z
)
]
=
P
X
-
h
[
T
-
T
0
]
+
ɛσ
[
T
4
-
T
0
4
]
wherein k is thermal conductivity, h is heat transfer coefficient, ε is emissivity, σ is Stefan-Boltzman constant, T is temperature, T 0 is ambient temperature, x is an X-coordinate in a three dimensional space, y is a Y-coordinate in a three dimensional space, z is a Z-coordinate in a three dimensional space, and P x is a three-dimensional Gaussian laser beam distribution; and
(b) forming the stent material into a cylindrical shape around a central axis, wherein the one or more dimples protrude outwardly away from the central axis, to produce a dimpled stent.
2 . The method of claim 1 , wherein P x is P g , wherein P g is Gaussian heat flux, and wherein P g is defined by the equation:
P
g
=
P
0
π
r
0
2
exp
-
⌊
x
2
+
y
2
r
0
2
⌋
wherein P 0 is laser input power, r 0 is radius of the laser beam at which laser power transverse intensity decreases to 1/e 2 , and wherein x, y, z are Cartesian coordinates with y along a center axis of the beam and with x and z in a plane orthogonal to the center axis of the beam and wherein beam intensity distribution is axisymmetric in a x-z plane.
3 . The method of claim 1 , wherein P x is P th , wherein P th is top hat heat flux, and wherein P th is defined by the equation:
P
th
=
P
0
π
r
0
2
exp
-
[
x
2
+
y
2
r
0
2
]
n
wherein n→∞, P 0 is laser input power, r 0 is radius of the laser beam at which laser power transverse intensity decreases to 1/e 2 , and wherein x, y, z are Cartesian coordinates with y along a center axis of the beam and with x and z in a plane orthogonal to the center axis of the beam and wherein beam intensity distribution is axisymmetric in a x-z plane.
4 . The method of claim 1 , wherein P x is P db , wherein P db is dumbbell heat flux, and wherein P db is defined by the equation:
P
db
=
2
P
0
π
r
0
2
(
x
r
0
)
2
exp
-
[
x
2
+
y
2
r
0
2
]
2
wherein P 0 is laser input power, r 0 is radius of the laser beam at which laser power transverse intensity decreases to 1/e 2 , and wherein x, y, z are Cartesian coordinates with y along a center axis of the beam and with x and z in a plane orthogonal to the center axis of the beam and wherein beam intensity distribution is axisymmetric in a x-z plane.
5 . The method of claim 1 , wherein the stent material is a titanium alloy, cobalt-chrome alloy, or stainless steel.
6 . The method of claim 1 , further comprising the step of choosing a laser to generate a laser beam, wherein the laser is a Neodymium-Doped Yttrium Aluminum Garnet (Nd:Y 3 Al 5 O 12 ) laser.
7 . The method of claim 1 , further comprising the step of choosing a laser to generate a laser beam, wherein the laser operates at a laser power of 500 W to 1800 W.
8 . The method of claim 1 , further comprising the step of using a Multiphysics computational model to predict and define features of the one or more dimples produced at the targeted surface areas.
9 . The method of claim 8 , wherein a selective governing equation based on heat transfer for the Multiphysics computational model is defined by the equation:
ρC
p
[
∂
T
∂
t
]
(
x
,
y
,
z
)
=
k
{
[
∂
2
T
∂
x
2
]
(
y
,
z
,
t
)
+
[
∂
2
T
∂
y
2
]
(
z
,
x
,
t
)
+
[
∂
2
T
∂
z
2
]
(
x
,
y
,
t
)
}
wherein k is the thermal conductivity, C p is specific heat and ρ is density of the stent material.
10 . The method of claim 8 , wherein width and depth of the one or more dimples produced at the targeted surface areas are determined based on the Multiphysics computational model.
11 . The dimpled stent produced by the method of claim 1 .
12 . A dimpled stent, comprising:
circumferential walls enclosing a cylindrical inner space surrounding a central axis, wherein the circumferential walls comprise one or more laser produced dimples protruding outwardly away from the central axis to create one or more dimpled spaces in outer edges of the cylindrical inner space.
13 . The dimpled stent of claim 12 , wherein the dimpled stent is about 30 mm long and about 3.5 mm in diameter, wherein the circumferential walls are about 0.1 mm thick, and wherein the dimples have a depth of about 0.12 mm and a width of about 0.6 mm.
14 . A dimpled stent, comprising:
a portion of stent material comprising adjacent rows of dimples protruding outwardly from the stent material, wherein each row of dimples comprises consecutive dimples, wherein each dimple has a depth d and a width w, wherein the dimples have a pitch P and a pitch R, wherein pitch P is spacing between centers of two consecutive dimples in a given row of dimples and P ranges from 1.8 w to 2.2 w, and wherein pitch R is spacing between centers of two dimples in two adjacent rows of dimples and R ranges from 1.8 w to 2.2 w.
15 . The dimpled stent of claim 14 , wherein each dimple has a depth between about 0.25 mm and 0.57 mm and a width between about 0.9 mm and 3.2 mm.
16 . The dimpled stent of claim 14 , wherein the portion of stent material is formed into a cylindrical tube shape wherein the dimples protrude outwardly from the cylindrical tube shape.
17 . A dimpled stent, comprising:
a portion of stent material comprising adjacent rows of dimples protruding outwardly from the stent material, wherein each row of dimples comprises consecutive dimples, wherein each dimple has a depth d and a width w or w′, wherein the dimples have a pitch P and a pitch R, wherein pitch P is spacing between centers of two consecutive dimples in a given row of dimples and P ranges from 1.8 times (w+w′) and 2.2 times (w+w′), and wherein pitch R is spacing between centers of two dimples in two adjacent rows of dimples and R ranges from 1.8 w and 2.2 w.
18 . The dimpled stent of claim 17 , wherein each dimple has a depth between about 0.25 mm and 0.57 mm and a width between about 0.9 mm and 3.2 mm.
19 . The dimpled stent of claim 17 , wherein the portion of stent material is formed into a cylindrical tube shape wherein the dimples protrude outwardly from the cylindrical tube shape.Cited by (0)
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